You may be interested to know that the Nmap Scripting Engine (NSE) also does this: https://github.com/nmap/nmap/blob/5325fa143c8a2a1f0ad7aa77b856c5e5c036ac46/nse_main.lua#L176-L213
Nice to learn that the problem of nested coroutines appears in other software too!
It's good to see you generalized it into a library. I'm curious, do you have an instance where there is more than one level of nesting?
No, currently i only use nested coroutines with two levels: iterators in redis-lua (https://github.com/nrk/redis-lua) and copas (https://github.com/keplerproject/copas) in the underlying sockets. To make them work together, i had to patch both libraries. The main problem in using the nested coroutines library is that, usually, Lua scripts use the global `coroutine` variable, instead of creating a local copy of it. So we can't just replace `_G.coroutine` with a nestable one before requiring the module. Search for instance the use of `coroutine` in: * https://github.com/keplerproject/copas/blob/master/src/copas.lua * https://github.com/nrk/redis-lua/blob/version-2.0/src/redis.lua If modules used a local `coroutine` variable, we could at least monkey-patch libraries as below: local coromake = require "coroutine.make" _G.coroutine = coromake () local copas = require "copas" _G.coroutine = coromake () local redis = require "redis" _G.coroutine = coromake () The best solution being, of course, to use coronest in those libraries ;-)